Genetic footprints of Iberian cattle in America 500 years after the arrival of Columbus.

BACKGROUND: American Creole cattle presumably descend from animals imported from the Iberian Peninsula during the period of colonization and settlement, through different migration routes, and may have also suffered the influence of cattle directly imported from Africa. The introduction of European cattle, which began in the 18th century, and later of Zebu from India, has threatened the survival of Creole populations, some of which have nearly disappeared or were admixed with exotic breeds. Assessment of the genetic status of Creole cattle is essential for the establishment of conservation programs of these historical resources. METHODOLOGY/PRINCIPAL FINDINGS: We sampled 27 Creole populations, 39 Iberian, 9 European and 6 Zebu breeds. We used microsatellite markers to assess the origins of Creole cattle, and to investigate the influence of different breeds on their genetic make-up. The major ancestral contributions are from breeds of southern Spain and Portugal, in agreement with the historical ports of departure of ships sailing towards the Western Hemisphere. This Iberian contribution to Creoles may also include some African influence, given the influential role that African cattle have had in the development of Iberian breeds, but the possibility of a direct influence on Creoles of African cattle imported to America can not be discarded. In addition to the Iberian influence, the admixture with other European breeds was minor. The Creoles from tropical areas, especially those from the Caribbean, show clear signs of admixture with Zebu. CONCLUSIONS/SIGNIFICANCE: Nearly five centuries since cattle were first brought to the Americas, Creoles still show a strong and predominant signature of their Iberian ancestors. Creole breeds differ widely from each other, both in genetic structure and influences from other breeds. Efforts are needed to avoid their extinction or further genetic erosion, which would compromise centuries of selective adaptation to a wide range of environmental conditions.

Methylation-specific PCR analysis in Col8A1 promoter in Creole cattle carrier of rob(1; 29)

Robertsonian translocation (rob(1;29)) is the most frequent structural chromosomal abnormality in cattle. Heterozygous carriers have a normal phenotype but show a 3-5 percent decrease in fertility. Chromatin decondensation was evaluated similar to the inactive X chromosome when submitted to demethylating agent. Based on this result, and the concept that imprinted genes are essential in embryonic development, we decided to query genes located on BTA1 and BTA29 that could undergo genome imprinting. The collagen typeVIII- alpha 1 (Col8A1) acted on extracellular matrix structural proteins. DNA bisulfite conversion and sequentiation methods were used to compare its differential methylation patterns. It was performed on eight Creole cattle DNA blood samples from normal and rob(1;29) carriers. An in silico screening for CpG islands in its promoter uncovered a single region of 454 bp prone to methylation. BiQ-Analizer software was used to show the selective conversion of unmethylated cytosines to uracils obtaining the following results: unmethylated CpGs: 0.000 (0 cases), methylated CpGs: 0.802 (77 cases) and CpGs not present: 0.198 (19 cases). No differences between samples were observed in this highly methylated region. This technique was successfully applied so it is a straightforward methodology that can be utilized to evaluate different tissue associated to specific gene expression.

Sex chromosomes behavior and G-banding treatment of male meiosis in nuptial gift-giving spiders of the family Trechaleidae.

Preliminary genetic studies in Trechaleidae spider family show high variation in sex chromosomes and high heterocigocity, suggesting high chromatin plasticity. The trechaleids Paratrechalea ornata, Trechalea bucculenta and Trechaleoides biocellata are present in Uruguay. Males offering nuptial gifts during courtship have been reported in P. ornata and T. bucculenta but not in T. biocellata. Nuptial gifts are an inherited trait probably highly affected by environmental factors, which play an important role in gene expression. We hypothesize that this trait could be associated with tissue-specific genes existing in G-bands. We investigate the male meiosis in these 3 species, their sex chromosome system and the effects of G-banding on their chromosomes, and elucidate genetic differences among them. Meiotic stages of the 3 species were submitted to Giemsa-staining and G-banding treatments. We observed a haploid number of n= 11 in P. ornata and n= 13 in both T. bucculenta and T. biocellata. Males from the 3 species presented an X(1) X(2) 0 sex chromosome system, which is suggested as ancestral in Araneae. In P. ornata and T. bucculenta, both sex chromosomes were together and aligned in parallel until the segregation during anaphase I. In contrast to these species, sex chromosomes of T. biocellata usually remained distant from each other until diakinesis when they were observed associated in parallel disposition. Interstitial G-bands were similar in P. ornata and T. bucculenta, and they both differed from those in T. biocellata. The special behavior of sex chromosomes in T. biocellata as well as the different G-banding pattern of this species suggests the existence of novel modifications in this species.

Analysis of the population structure of Uruguayan Creole cattle as inferred from milk major gene polymorphisms

The ancestors of Uruguayan Creole cattle were introduced by the Spanish conquerors in the XVII century, following which the population grew extensively and became semi-feral before the introduction of selected breeds. Today the Uruguayan Creole cattle genetic reserve consists of 575 animals. We used the tetra primer amplification refractory mutation system polymerase chain reaction (ARMS-PCR) to analyze the kappa-casein, beta-casein, alphaS1-casein and alpha-lactoalbumin gene polymorphisms and restriction fragment length polymorphism PCR (RFLP-PCR) for the beta-lactoglobulin and the acylCoA:diacyl glycerol acyltransferase 1 (DGAT1) genes. The kappa-casein and beta-lactoglobulin genes presented very similar A and B allele frequencies, while the alphas1-casein and alpha-lactoalbumin gene B alleles showed much higher frequencies than the corresponding A alleles. The beta-casein B allele was not found in the population sampled. There was a very high frequency of the DGAT1 gene A allele which is associated with low milk fat content and high milk yield. All loci were in Hardy-Weinberg equilibrium and the level of heterozygosity agreed with the high genetic diversity observed in a previous analysis of this population. Preservation of the allelic richness observed in the Uruguayan Creole cattle should be considered for future dairy management and livestock genetic improvement. The results also emphasize the value of the tetra primers ARMS-PCR technique as a rapid, easy and economical way of genotyping cattle breeds for milk gene single nucleotide polymorphisms.

Microsatellite analysis of a sample of Uruguayan Creole bulls (Bos taurus)

The Uruguayan Creole cattle genetic reserve consists of a herd of about 600 animals (bulls, cows and calves) located in an indigenous habitat of 650 hectares. In a previous study, a random sample from this herd showed high heterozygosity and a Hardy-Weinberg equilibrium for markers of major genes related to milk production. To study its genetic diversity we genotyped a sample of bulls (N = 19 out of 23 for the whole herd) using the PCR reaction with a set of 17 microsatellite markers. Between two and seven different alleles were identified per microsatellite in a total of 73 alleles. The expected mean heterozygosity (He) per locus was between 0.465 and 0.801, except for microsatellite HEL13 which gave a He value of 0.288. The expected mean heterozygosity was 0.623 and the polymorphic information content (PIC) was between 0.266 for HEL13 and 0.794 for CSSM66. The genetic diversity found in polymorphic markers in the breeding bulls of this Creole cattle population supports previous genetic analyses using major production genes and indicate that further studies should be carried out on this population to provide data of interest to cattle production.

Mapping and characterization of the dominant black colour locus in sheep.

Dominant black pigment synthesis in sheep is caused by alterations of the melanocortin-1 receptor (MC1-R) coding sequence. Using five bovine microsatellite markers we have mapped the sheep MC1-R gene to chromosome 14, corresponding to the location in other mammalian species. The existence of two independent mutations, both causing an amino acid substitution, in distantly related breeds of sheep, support the hypothesis that the observed black pigment synthesis is caused by a mutual effect of the two mutations. As similar mutations are found separately at both locations in dominant black variants of other animal species, it is also possible that any of the two mutations could be sufficient for a partial pigment switch.

Localisation of aphidicolin-induced break points in Holstein-Friesian cattle (Bos taurus) using RBG-banding.

Fragile sites (FS) seem to play a role in genome instability and may be involved in karyotype evolution and chromosome aberrations. The majority of common fragile sites are induced by aphidicolin. Aphidicolin was used at two different concentrations (0.15 and 0.30 microM) to study the occurrence of FS in the cattle karyotype. In this paper, a map of aphidicolin induced break points and fragile sites in cattle chromosomes was constructed. The statistical analysis indicated that any band with three or more breaks was significantly damaged (P<0.05). According to this result, 30 of the 72 different break points observed were scored as fragile sites. The Pearson correlation test showed a positive association between chromosome length and the number of fragile sites (r=0.54). On the contrary, 21 FS were identified on negative R bands while 9 FS were located on positive R bands.